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<html lang="en">

<head>
  <meta charset="UTF-8">
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  <title>Document</title>
</head>

<body>
  <div>
    <span>
      <span>
        <span>数学</span>
        <span>英语</span>
      </span>
    </span>
  </div>
</body>
<style>
  div>span {
    font-size: 50px;
    color: blue;
    border: 1px solid red;
    background-color: yellow;
  }

  /* 大于的话 如果自身没有 优先父标签的样式 自身有 优先使用自身样式 */
  div>span>span {
    color: red;
    border: 1px solid blue;
    font-size: 30px;
  }

  div span span span:nth-child(1) {
    color: skyblue;
    font-size: 40px;
    /* border: 1px solid red; */
  }
</style>

</html>